| 南京北郊降水无机离子和有机酸的化学特征及来源分析 |
| 摘要点击 1980 全文点击 615 投稿时间：2019-11-06 修订日期：2019-12-25 |
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| 中文关键词 降水 水溶性离子 有机酸 源解析 正交矩阵因子模型(PMF) |
| 英文关键词 precipitation water-soluble ions organic acids source identification positive matrix factorization(PMF) |
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| 中文摘要 |
| 连续收集2016年12月至2017年11月期间的南京降水样品，分析主要无机离子和有机酸的化学特征及季节变化，运用正交矩阵因子模型法（PMF）进行源解析.结果表明，南京地区降水pH均值为5.6，离子总浓度雨量加权平均值为297.3 μmol·L-1，阳离子浓度依序为NH4+ > Ca2+ > K+ > Na+ > Mg2+，阴离子浓度则为NO3- > SO42- > Cl- > F-.总有机酸浓度雨量加权平均值为2.86 μmol·L-1，占总阴离子的2.2%.CHO2-、C2H3O2-和C2O42-是南京降水主要的有机酸，年雨量加权平均值分别是1.35、1.05和0.26 μmol·L-1.离子浓度总体表现出明显的冬春高和夏秋低的季节性变化，而总有机酸浓度夏季最高，春季次之，冬季最低，生长季节高于非生长季节，与较多的植被排放有关.运用甲酸和乙酸的比值（F/A）判定南京降水有机酸的主要来源为植物生长释放，有机物燃烧，机动车排放等直接来源，大气氧化等间接来源较少.南京降水无机离子和有机酸主要有5个来源贡献，海源和二次无机生成、生物质燃烧、陆源和垃圾焚烧、二次有机生成、生物排放和生物源二次生成，分别贡献40.0%、22.2%、22.0%、14.5%及1.3%. |
| 英文摘要 |
| Rainwater samples were collected in Nanjing from December 2016 to November 2017. Water-soluble ion and organic acid content in rainwater samples was determined to analyze the chemical characteristics of precipitation and their seasonality. The positive matrix factorization (PMF) model was employed to identify the potential sources of precipitation. The results show that the volume-weighted mean of pH in precipitation was 5.6, which was higher than the results of previous studies conducted in Nanjing. The volume-weighted mean of total ions was 297.3 μmol·L-1, and the concentrations of each species were in the order of NH4+ > Ca2+ > K+ > Na+ > Mg2+ for cations and NO3- > SO42- > Cl- > F- for anions. The volume-weighted mean of organic acids was 2.86 μmol·L-1, with organic acids accounting for 2.2% of the total anions. CHO2-, C2H3O2-, and C2O42- were the main organic acids in precipitation with annual volume-weighted means of 1.35, 1.05, and 0.26 μmol·L-1, respectively. A significant seasonality was observed for the ions and organic acids. The volume-weighted mean of inorganic ions was higher in winter and spring compared to those in summer and autumn. On the other hand, the volume-weighted mean of total organic acids was the highest in summer, followed by spring, and the lowest in winter. High concentrations of organic acids in the summer can be attributed to the biogenic emissions from plants. The ratio of formic and acetic (F/A) showed that organic acids mainly originated from primary emissions (e.g., biogenic emissions, combustion of organics, and traffic emissions) rather than atmospheric oxidation processes. Using the PMF model, we found that marine sources and secondary inorganic products (40.0%) were the predominant sources of inorganic ions and organic acids in precipitation, followed by burning of biomass (22.2%), continental origin and waste incineration (22.0%), secondary organic products (14.5%), and biological emissions along with their secondary products (1.3%). |
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